CN102521439B - Method for calculating quenching medium heat exchange coefficient by combining finite element method with inverse heat conduction method - Google Patents

Abstract

The invention discloses a method for calculating a quenching medium heat exchange coefficient by combining a finite element method with an inverse heat conduction method, which relates to a method for calculating a quenching medium heat exchange coefficient. The method comprises the following steps of: using a probe body, testing by an experiment to obtain the cooling curve of an internal point of the body, establishing a finite element model of the probe body, simulating a temperature field, and verifying the one-dimensional property of a problem; establishing a one-dimensional heat conduction micro equation and a sensitive coefficient equation under a coordinate system, and solving the heat-flow density value of the surface of the body surface by using the inverse heat conduction method; and verifying the measured temperature of the internal point of the probe in comparison to a calculated value, namely the heat exchange coefficient of the quenching medium calculated according to the Newton heat exchange law, so that the solution accuracy is ensured. The method is used for calculating the heat exchange coefficient of quenching medium.

Description

Method in conjunction with finite element method and the inverse heat conduction method calculating hardening media coefficient of heat transfer

Technical field

The present invention relates to a kind of method of calculating the hardening media coefficient of heat transfer, belong to metal fever working process parameter design field.

Background technology

Quenching Treatment is a kind of very important heat treatment mode of part in actual production, to obtain the mechanical property needing, and hardening media is undoubtedly most important influence factor, the embodiment of the essential of hardening media is the size of the coefficient of heat transfer between itself and metal surface.Seeking accurate method obtains the size of the coefficient of heat transfer and has important practical meaning in engineering.At present, the main method of studying this problem is the hot computing method of anti-pass, and this method is the discrete computing method of a kind of mathematics of theory, has certain inevitable error, cause accurately controlling the quench cooling rate of industrial part, cooling velocity is difficult to measure.

Summary of the invention

The object of the invention is to there is error in order to solve the method for obtaining the coefficient of heat transfer by the hot computing method of anti-pass, cause accurately controlling the quench cooling rate of industrial part, cooling velocity is difficult to the problem of measuring, and then provides a kind of combination finite element method and inverse heat conduction method to calculate the method for the hardening media coefficient of heat transfer.

The present invention is achieved by following proposal: in conjunction with the method for finite element method and the inverse heat conduction method calculating hardening media coefficient of heat transfer, the detailed process of the method for the described calculating hardening media coefficient of heat transfer is:

Step 1, the probe body that inside is inserted with to thermopair are heated to after 860 ℃ of insulations evenly in heating furnace, to be no more than the transfer time of 2s, quench rapidly in hardening media, and quench media temperature is set as T _w, adopt computer system to record the temperature of the probe body interior unique point B3 being recorded by thermopair, and draw cooling curve, obtain the cooling curve of this hardening media at this temperature;

Step 2, based on ABAQUS finite element platform, adopt the method for finite element to set up the finite element symmetry model of probe body, the physical function parameter of input probe bulk material and mechanical property parameters, set 850 ℃ of initial temperatures, sets quench media temperature T _w, choose coefficient of heat transfer maximum value, choose surface characteristics point A1 and the inter characteristic points B1 of one-dimensional model, choose surface characteristics point A2 and the inter characteristic points B2 of three-dimensional model, the surface characteristics point A1 of one-dimensional model and the surface characteristics point A2 of three-dimensional model are same position point, one-dimensional model inter characteristic points B1, three-dimensional model inter characteristic points B2 and probe body interior unique point B3 are same point, then adopt respectively one-dimensional model and three-dimensional model carry out analog computation and compare, probe body overlaps at the cooling curve of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2, probe body overlaps at the cooling curve of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2, the one dimension character that checking heat transfer problem meets,

Step 3, according to law of conservation of energy and Fourier law, set up the one-dimensional heat conduction differential equation under cylindrical-coordinate system, provide starting condition and the boundary condition of equation, and definition and temperature have the sensitivity coefficient equation of same form, provide starting condition and the boundary condition of sensitivity coefficient equation, utilize inverse heat conduction method to solve the heat flow density value of probe body surface;

The one-dimensional heat conduction differential equation under cylindrical-coordinate system is:

$\mathrm{\ρc}\frac{\∂T}{\∂t}=\frac{1}{r}\frac{\∂}{\∂r}\left(\mathrm{\λr}\frac{\∂T}{\∂r}\right)---\left(1\right)$

In formula, ρ is density; C is specific heat capacity; T is probe body surface temperature; T is the time; λ is heat-conduction coefficient; R is the radius of probe body;

Starting condition is:

T(r，t _M-1)＝T _M-1(r) (2)

T in formula _m-1for the M-1 moment; T _m-1(r) be t _m-1temperature Distribution constantly;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}{q}_M=\mathrm{const}& t_{M-1}<t<t_M\\ q\left(t\right)& t>t_M\end{array}\right.---\left(3\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(4\right)$

In formula, R is the real radius value of probe body; T in formula _mfor the M moment; Heat flow density q _mfor constant; Q (t) is t heat flow density value constantly;

Definition sensitivity coefficient, for the sensitivity of probe body interior point thermometric error, is that temperature is about the first derivative of heat flow density;

Sensitivity coefficient expression formula is:

$\mathrm{\&rho;c}\frac{\&PartialD;X_M}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;X_M}{\&PartialD;r}\right)---\left(5\right)$

X in formula _mfor sensitivity coefficient;

Starting condition is:

X _M(r，t _M-1)＝0 (6)

X in formula _mfor sensitivity coefficient;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;X_M}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}1& t_{M-1}<t<t_M\\ 0& t>t_M\end{array}\right.---\left(7\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(8\right)$

Sensitivity coefficient is revised heat flow density value, utilizes inverse heat conduction method to solve M heat flow density value constantly, repeatedly calculates the heat flow density value q of whole quenching process;

Step 4, according to newton's heat exchange law, calculate the coefficient of heat transfer of metal and dielectric surface, obtained the coefficient of heat transfer of medium; Newton's heat exchange law expression formula is:

q＝h(T-T _w) (9)

In formula, q is heat flow density value, and h is the coefficient of heat transfer, (T-T _w) be surface temperature of probe and the difference of setting medium temperature;

The temperature of the probe body interior unique point B3 in the technical program, thermopair in step 1 being recorded, and the body of popping one's head in the cooling curve of drawing and step 2 contrasts at the cooling curve of three-dimensional model condition inter characteristic points B2, both coincide, and have verified the accuracy that the coefficient of heat transfer solves.

Beneficial effect of the present invention: the present invention proposes the method in conjunction with finite element method and the inverse heat conduction method calculating hardening media coefficient of heat transfer, ABAQUS finite element software based on ripe, guarantee confidence level and the accuracy of result of calculation, in conjunction with traditional inverse heat conduction method, with more accurate and more reliable method, removed to solve on this basis the coefficient of heat transfer of hardening media.The proposition of the method, controlled accurately the quench cooling rate of industrial part, avoid cooling velocity to be difficult to the problem of measuring, and the method is promoted, cooling curve by test different medium is tried to achieve itself and the coefficient of heat transfer of metal surface, then designs hardening media, makes part in industry, obtain the mechanical property being satisfied with, adapt under various environment the performance requirement of military service.

Accompanying drawing explanation

Fig. 1 is the structural representation of probe body;

Fig. 2 is pop one's head in while being water cooling curve (3 cooling curves that represent to pop one's head in when medium temperatures are 25 ℃ body interior unique point B3 in figure of body interior unique point B3 of hardening media, 4 cooling curves that represent to pop one's head in when medium temperatures are 45 ℃ body interior unique point B3,5 cooling curves that represent to pop one's head in when medium temperatures are 60 ℃ body interior unique point B3,6 cooling curves that represent to pop one's head in when medium temperatures are 80 ℃ body interior unique point B3);

Fig. 3 is the three-dimensional model of the probe body based on the foundation of ABAQUS finite element platform;

Fig. 4 is the one-dimensional model of the probe body based on the foundation of ABAQUS finite element platform;

Fig. 5 is that probe body is at the cooling curve comparison diagram of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2;

Fig. 6 is that probe body is at the cooling curve comparison diagram of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2;

Fig. 7 is the cooling curve and the cooling curve comparison diagram of probe body at three-dimensional model condition inter characteristic points B2 of the probe body interior unique point B3 that records of thermopair.

Embodiment

Embodiment one: in conjunction with Fig. 1 to Fig. 7, present embodiment is described, the combination finite element method of present embodiment and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, and the detailed process of the method for the described calculating hardening media coefficient of heat transfer is:

Step 1, the probe body 1 that inside is inserted with to thermopair 2 are heated to after 860 ℃ of insulations evenly in heating furnace, to be no more than the transfer time of 2s, quench rapidly in hardening media, and quench media temperature is set as T _w, adopt computer system to record the temperature of the probe body 1 inter characteristic points B3 being recorded by thermopair 2, and draw cooling curve, obtain the cooling curve of this hardening media at this temperature;

Step 2, based on ABAQUS finite element platform, adopt the method for finite element to set up the finite element symmetry model of probe body 1, physical function parameter and the mechanical property parameters of input probe body 1 material, set 850 ℃ of initial temperatures, sets quench media temperature T _w, choose coefficient of heat transfer maximum value, choose surface characteristics point A1 and the inter characteristic points B1 of one-dimensional model, choose surface characteristics point A2 and the inter characteristic points B2 of three-dimensional model, the surface characteristics point A1 of one-dimensional model and the surface characteristics point A2 of three-dimensional model are same position point, one-dimensional model inter characteristic points B1, three-dimensional model inter characteristic points B2 and probe body 1 inter characteristic points B3 are same point, then adopt respectively one-dimensional model and three-dimensional model carry out analog computation and compare, probe body 1 overlaps at the cooling curve of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2, probe body 1 overlaps at the cooling curve of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2, the one dimension character that checking heat transfer problem meets,

Step 3, according to law of conservation of energy and Fourier law, set up the one-dimensional heat conduction differential equation under cylindrical-coordinate system, provide starting condition and the boundary condition of equation, and definition and temperature have the sensitivity coefficient equation of same form, provide starting condition and the boundary condition of sensitivity coefficient equation, utilize inverse heat conduction method to solve the heat flow density value on probe body 1 surface;

The one-dimensional heat conduction differential equation under cylindrical-coordinate system is:

$\mathrm{\&rho;c}\frac{\&PartialD;T}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;T}{\&PartialD;r}\right)---\left(1\right)$

In formula, ρ is density; C is specific heat capacity; T is probe body surface temperature; T is the time; λ is heat-conduction coefficient; R is the radius of probe body 1;

Starting condition is:

T(r，t _M-1)＝T _M-1(r) (2)

T in formula _m-1for the M-1 moment; T _m-1(r) be t _m-1temperature Distribution constantly;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}{q}_M=\mathrm{const}& t_{M-1}<t<t_M\\ q\left(t\right)& t>t_M\end{array}\right.---\left(3\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(4\right)$

In formula, R is the real radius value of probe body 1; T in formula _mfor the M moment; Heat flow density q _mfor constant; Q (t) is t heat flow density value constantly;

Definition sensitivity coefficient, for the sensitivity of probe body 1 internal point thermometric error, is that temperature is about the first derivative of heat flow density;

Sensitivity coefficient expression formula is:

$\mathrm{\&rho;c}\frac{\&PartialD;X_M}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;X_M}{\&PartialD;r}\right)---\left(5\right)$

X in formula _mfor sensitivity coefficient;

Starting condition is:

X _M(r，t _M-1)＝0 (6)

X in formula _mfor sensitivity coefficient;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;X_M}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}1& t_{M-1}<t<t_M\\ 0& t>t_M\end{array}\right.---\left(7\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(8\right)$

Sensitivity coefficient is revised heat flow density value, utilizes inverse heat conduction method to solve M heat flow density value constantly, repeatedly calculates the heat flow density value q of whole quenching process;

Step 4, according to newton's heat exchange law, calculate the coefficient of heat transfer of metal and dielectric surface, obtained the coefficient of heat transfer of medium; Newton's heat exchange law expression formula is:

q＝h(T-T _w) (9)

In formula, q is heat flow density value, and h is the coefficient of heat transfer, (T-T _w) be surface temperature of probe and the difference of setting medium temperature;

The temperature of the probe body 1 inter characteristic points B3 in present embodiment, thermopair in step 12 being recorded, and the body 1 of popping one's head in the cooling curve of drawing and step 2 contrasts at the cooling curve of three-dimensional model condition inter characteristic points B2, both coincide, and have verified the accuracy that the coefficient of heat transfer solves.

Embodiment two: the hardening media in the step 1 of present embodiment is water, No. 20 machine oil or UCON-A (water-soluble polymers) quenching medium.

Embodiment three: when the hardening media in the step 1 of present embodiment is water, quench media temperature is set as 25 ℃, 45 ℃, 60 ℃ or 80 ℃.The temperature of determining hardening media according to the serviceability temperature in hardening media physical property and reality, cooling curve is referring to Fig. 2.

Embodiment four: when the hardening media in the step 1 of present embodiment is No. 20 machine oil, quench media temperature is set as 25 ℃, 45 ℃ or 60 ℃.According to the serviceability temperature in hardening media physical property and reality, determine the temperature of hardening media.

Embodiment five: when the hardening media in the step 1 of present embodiment is UCON-A (water-soluble polymers) quenching medium, quench media temperature is set as 25 ℃, 45 ℃ or 60 ℃.According to the serviceability temperature in hardening media physical property and reality, determine the temperature of hardening media.

Embodiment six: the linear dimension of the probe body 1 in the step 1 of present embodiment is Φ 12.5 * 60mm, the material of probe body 1 is nickel chromium triangle iron-based solid solution strengthened alloy, the diameter of thermopair 2 is 1.5mm.

Embodiment seven: the combination finite element method of present embodiment and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, and the detailed process of the method for the described calculating hardening media coefficient of heat transfer is:

Step 1, the probe body 1 that inside is inserted with to thermopair 2 are heated to after 860 ℃ of insulations evenly in heating furnace, to be no more than the transfer time of 2s, quench rapidly in hardening media, and quench media temperature is set as T _w, adopt computer system to record the temperature of the probe body 1 inter characteristic points B3 being recorded by thermopair 2, and draw cooling curve, obtain the cooling curve of this hardening media at this temperature;

The linear dimension of probe body 1 is Φ 12.5 * 60mm, and the material of probe body 1 is nickel chromium triangle iron-based solid solution strengthened alloy (Incone1600), and the diameter of thermopair 2 is 1.5mm, and hardening media is water, quench media temperature T _wbe set as 25 ℃; Cooling curve is referring to Fig. 2;

Step 2, based on ABAQUS finite element platform, adopt the finite element symmetry model of the method foundation probe body 1 of finite element, physical function parameter and the mechanical property parameters of input probe body 1 nickel chromium triangle iron-based solid solution strengthened alloy material, set 850 ℃ of initial temperatures, set the temperature T of hardening media water _wbe 25 ℃, choose coefficient of heat transfer maximum value 22000W (m ²* K), choose surface characteristics point A1 and the inter characteristic points B1 of one-dimensional model, choose surface characteristics point A2 and the inter characteristic points B2 of three-dimensional model, the surface characteristics point A1 of one-dimensional model and the surface characteristics point A2 of three-dimensional model are same position point, one-dimensional model inter characteristic points B1, three-dimensional model inter characteristic points B2 and probe body 1 inter characteristic points B3 are same point, then adopt respectively one-dimensional model and three-dimensional model carry out analog computation and compare, probe body 1 overlaps at the cooling curve of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2, probe body 1 overlaps at the cooling curve of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2, the one dimension character that checking heat transfer problem meets, referring to Fig. 3 to Fig. 6,

Step 3, according to law of conservation of energy and Fourier law, set up the one-dimensional heat conduction differential equation under cylindrical-coordinate system, provide starting condition and the boundary condition of equation, and definition and temperature have the sensitivity coefficient equation of same form, provide starting condition and the boundary condition of sensitivity coefficient equation, utilize inverse heat conduction method to solve the heat flow density value on probe body 1 surface;

The one-dimensional heat conduction differential equation under cylindrical-coordinate system is:

$\mathrm{\&rho;c}\frac{\&PartialD;T}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;T}{\&PartialD;r}\right)---\left(1\right)$

In formula, ρ is density; C is specific heat capacity; T is probe body surface temperature; T is the time; λ is heat-conduction coefficient; R is the radius of probe body 1;

Starting condition is:

T(r，t _M-1)＝T _M-1(r) (2)

T in formula _m-1for the M-1 moment; T _m-1(r) be t _m-1temperature Distribution constantly;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}{q}_M=\mathrm{const}& t_{M-1}<t<t_M\\ q\left(t\right)& t>t_M\end{array}\right.---\left(3\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(4\right)$

In formula, R is the real radius value of probe body 1; T in formula _mfor the M moment; Heat flow density q _mfor constant; Q (t) is t heat flow density value constantly;

Definition sensitivity coefficient, for the sensitivity of probe body 1 internal point thermometric error, is that temperature is about the first derivative of heat flow density;

Sensitivity coefficient expression formula is:

$\mathrm{\&rho;c}\frac{\&PartialD;X_M}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;X_M}{\&PartialD;r}\right)---\left(5\right)$

X in formula _mfor sensitivity coefficient;

Starting condition is:

X _M(r，t _M-1)＝0 (6)

X in formula _mfor sensitivity coefficient;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;X_M}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}1& t_{M-1}<t<t_M\\ 0& t>t_M\end{array}\right.---\left(7\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(8\right)$

Sensitivity coefficient is revised heat flow density value, utilizes inverse heat conduction method to solve M heat flow density value constantly, repeatedly calculates the heat flow density value q of whole quenching process; Sensitivity coefficient and temperature have the differential equation of same form, can adopt finite difference to solve heat flow density value q;

Calculate originally, suppose that heat flow density value is zero, by sensitivity coefficient, heat flow density value is revised, make modified value enough little;

Step 4, according to newton's heat exchange law, calculate the coefficient of heat transfer of metal and dielectric surface, obtained the coefficient of heat transfer of medium; Newton's heat exchange law expression formula is:

q＝h(T-T _w) (9)

In formula, q is heat flow density value, and h is the coefficient of heat transfer, (T-T _w) be surface temperature of probe and the difference of setting medium temperature;

The temperature of the probe body 1 inter characteristic points B3 in present embodiment, thermopair in step 12 being recorded, and the body 1 of popping one's head in the cooling curve of drawing and step 2 contrasts at the cooling curve of three-dimensional model condition inter characteristic points B2, both coincide, and have verified the accuracy that the coefficient of heat transfer solves.

Claims (7)

1. in conjunction with a method for finite element method and the inverse heat conduction method calculating hardening media coefficient of heat transfer, it is characterized in that: the detailed process of the method for the described calculating hardening media coefficient of heat transfer is:

Step 1, the probe body (1) that inside is inserted with to thermopair (2) are heated to after 860 ℃ of insulations evenly in heating furnace, to be no more than the transfer time of 2s, quench rapidly in hardening media, and quench media temperature is set as T _w, adopt computer system to record the temperature of probe body (1) the inter characteristic points B3 being recorded by thermopair (2), and draw cooling curve, obtain the cooling curve of this hardening media at this temperature;

Step 2, based on ABAQUS finite element platform, adopt the finite element symmetry model of the method foundation probe body (1) of finite element, physical function parameter and the mechanical property parameters of input probe body (1) material, set 850 ℃ of initial temperatures, sets quench media temperature T _w, choose coefficient of heat transfer maximum value, choose surface characteristics point A1 and the inter characteristic points B1 of one-dimensional model, choose surface characteristics point A2 and the inter characteristic points B2 of three-dimensional model, the surface characteristics point A1 of one-dimensional model and the surface characteristics point A2 of three-dimensional model are same position point, one-dimensional model inter characteristic points B1, three-dimensional model inter characteristic points B2 and probe body (1) inter characteristic points B3 are same point, then adopt respectively one-dimensional model and three-dimensional model carry out analog computation and compare, probe body (1) overlaps at the cooling curve of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2, probe body (1) overlaps at the cooling curve of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2, the one dimension character that checking heat transfer problem meets,

Step 3, according to law of conservation of energy and Fourier law, set up the one-dimensional heat conduction differential equation under cylindrical-coordinate system, provide starting condition and the boundary condition of equation, and definition and temperature field have the sensitivity coefficient equation of same form, provide starting condition and the boundary condition of sensitivity coefficient equation, utilize inverse heat conduction method to solve the heat flow density value on probe body (1) surface;

The one-dimensional heat conduction differential equation under cylindrical-coordinate system is:

$\mathrm{\&rho;c}\frac{\&PartialD;T}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;T}{\&PartialD;r}\right)---\left(1\right)$

In formula, ρ is density; C is specific heat capacity; T is probe body surface temperature; T is the time; λ is heat-conduction coefficient; r

Radius for probe body (1);

Starting condition is:

T(r,t _M-1)=T _M-1(r) (2)

T in formula _m-1for the M-1 moment; T _m-1(r) be t _m-1temperature Distribution constantly;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}{q}_M=\mathrm{const}& t_{M-1}<t<t_M\\ q\left(t\right)& t>t_M\end{array}\right.---\left(3\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(4\right)$

In formula, R is the real radius value of probe body (1); T in formula _mfor the M moment; Heat flow density q _mfor constant; Q (t) is t heat flow density value constantly;

Definition sensitivity coefficient, for the sensitivity of probe body (1) internal point thermometric error, is that temperature is about the first derivative of heat flow density;

Sensitivity coefficient expression formula is:

$\mathrm{\&rho;c}\frac{\&PartialD;X_M}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{{\&PartialD;X}_M}{\&PartialD;r}\right)---\left(5\right)$

X in formula _mfor sensitivity coefficient;

Starting condition is:

X _M(r,t _M-1)=0 (6)

X in formula _mfor sensitivity coefficient;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{{\&PartialD;X}_M}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}1& t_{M-1}<t<t_M\\ 0& t>t_M\end{array}\right.---\left(7\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(8\right)$

Sensitivity coefficient is revised heat flow density value, utilizes inverse heat conduction method to solve M heat flow density value constantly, repeatedly calculates the heat flow density value q of whole quenching process;

Step 4, according to newton's heat exchange law, calculate the coefficient of heat transfer of metal and dielectric surface, obtained the coefficient of heat transfer of medium; Newton's heat exchange law expression formula is:

q=h(T-T _w) (9)

In formula, q is heat flow density value, and h is the coefficient of heat transfer, (T-T _w) be surface temperature of probe and the difference of setting medium temperature.

2. combination finite element method according to claim 1 and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, it is characterized in that: the hardening media in step 1 is water, No. 20 machine oil or UCON-A quenching medium.

3. combination finite element method according to claim 2 and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, it is characterized in that: when the hardening media in step 1 is water, quench media temperature is set as 25 ℃, 45 ℃, 60 ℃ or 80 ℃.

4. combination finite element method according to claim 2 and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, it is characterized in that: when the hardening media in step 1 is No. 20 machine oil, quench media temperature is set as 25 ℃, 45 ℃ or 60 ℃.

5. combination finite element method according to claim 2 and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, it is characterized in that: when the hardening media in step 1 is UCON-A quenching medium, quench media temperature is set as 25 ℃, 45 ℃ or 60 ℃.

6. combination finite element method according to claim 1 and inverse heat conduction method calculate the method for the hardening media coefficient of heat transfer, it is characterized in that: the linear dimension of the probe body (1) in step 1 is Φ 12.5 * 60mm, the material of probe body (1) is nickel chromium triangle iron-based solid solution strengthened alloy, and the diameter of thermopair (2) is 1.5mm.

7. in conjunction with a method for finite element method and the inverse heat conduction method calculating hardening media coefficient of heat transfer, it is characterized in that: the detailed process of the method for the described calculating hardening media coefficient of heat transfer is:

Step 1, the probe body (1) that inside is inserted with to thermopair (2) are heated to after 860 ℃ of insulations evenly in heating furnace, to be no more than the transfer time of 2s, quench rapidly in hardening media, and quench media temperature is set as T _w, adopt computer system to record the temperature of probe body (1) the inter characteristic points B3 being recorded by thermopair (2), and draw cooling curve, obtain the cooling curve of this hardening media at this temperature;

The linear dimension of probe body (1) is Φ 12.5 * 60mm, and the material of probe body (1) is nickel chromium triangle iron-based solid solution strengthened alloy, and the diameter of thermopair (2) is 1.5mm, and hardening media is water, quench media temperature T _wbe set as 25 ℃;

Step 2, based on ABAQUS finite element platform, adopt the finite element symmetry model of the method foundation probe body (1) of finite element, physical function parameter and the mechanical property parameters of input probe body (1) nickel chromium triangle iron-based solid solution strengthened alloy material, set 850 ℃ of initial temperatures, set the temperature T of hardening media water _wbe 25 ℃, choose coefficient of heat transfer maximum value 22000W (m ²* K), choose surface characteristics point A1 and the inter characteristic points B1 of one-dimensional model, choose surface characteristics point A2 and the inter characteristic points B2 of three-dimensional model, the surface characteristics point A1 of one-dimensional model and the surface characteristics point A2 of three-dimensional model are same position point, one-dimensional model inter characteristic points B1, three-dimensional model inter characteristic points B2 and probe body (1) inter characteristic points B3 are same point, then adopt respectively one-dimensional model and three-dimensional model carry out analog computation and compare, probe body (1) overlaps at the cooling curve of one-dimensional model condition lower surface unique point A1 and three-dimensional model condition lower surface unique point A2, probe body (1) overlaps at the cooling curve of one-dimensional model condition inter characteristic points B1 and three-dimensional model condition inter characteristic points B2, the one dimension character that checking heat transfer problem meets,

Step 3, according to law of conservation of energy and Fourier law, set up the one-dimensional heat conduction differential equation under cylindrical-coordinate system, provide starting condition and the boundary condition of equation, and definition and temperature field have the sensitivity coefficient equation of same form, provide starting condition and the boundary condition of sensitivity coefficient equation, utilize inverse heat conduction method to solve the heat flow density value on probe body (1) surface;

The one-dimensional heat conduction differential equation under cylindrical-coordinate system is:

$\mathrm{\&rho;c}\frac{\&PartialD;T}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{\&PartialD;T}{\&PartialD;r}\right)---\left(1\right)$

In formula, ρ is density; C is specific heat capacity; T is probe body surface temperature; T is the time; λ is heat-conduction coefficient; r

Radius for probe body (1);

Starting condition is:

T(r,t _M-1)=T _M-1(r) (2)

T in formula _m-1for the M-1 moment; T _m-1(r) be t _m-1temperature Distribution constantly;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}{q}_M=\mathrm{const}& t_{M-1}<t<t_M\\ q\left(t\right)& t>t_M\end{array}\right.---\left(3\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(4\right)$

In formula, R is the real radius value of probe body (1); T in formula _mfor the M moment; Heat flow density q _mfor constant; Q (t) is t heat flow density value constantly;

Definition sensitivity coefficient, for the sensitivity of probe body (1) internal point thermometric error, is that temperature is about the first derivative of heat flow density;

Sensitivity coefficient expression formula is:

$\mathrm{\&rho;c}\frac{\&PartialD;X_M}{\&PartialD;t}=\frac{1}{r}\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{\&lambda;r}\frac{{\&PartialD;X}_M}{\&PartialD;r}\right)---\left(5\right)$

X in formula _mfor sensitivity coefficient;

Starting condition is:

X _M(r,t _M-1)=0 (6)

X in formula _mfor sensitivity coefficient;

Boundary condition is:

$-\mathrm{\&lambda;}\frac{{\&PartialD;X}_M}{\&PartialD;r}{|}_{r=R}=\left\{\begin{array}{cc}1& t_{M-1}<t<t_M\\ 0& t>t_M\end{array}\right.---\left(7\right)$

$-\mathrm{\&lambda;}\frac{\&PartialD;T}{\&PartialD;r}{|}_{r=0}=0---\left(8\right)$

Sensitivity coefficient is revised heat flow density value, utilizes inverse heat conduction method to solve M heat flow density value constantly, repeatedly calculates the heat flow density value q of whole quenching process;

Step 4, according to newton's heat exchange law, calculate the coefficient of heat transfer of metal and dielectric surface, obtained the coefficient of heat transfer of medium; Newton's heat exchange law expression formula is:

q=h(T-T _w) (9)

In formula, q is heat flow density value, and h is the coefficient of heat transfer, (T-T _w) be surface temperature of probe and the difference of setting medium temperature.

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